Isfahan University of Technology
  • Isfahan, Isfahan, Iran
Recent publications
Stainless steel ASTM 316 L is often used in the food industry as contact material with protein-rich dairy products. It has to be welded at some locations for many of these contact materials. This study aimed at i) determining any combined effects of the presence of whey protein (WP) and welding-induced weaknesses on corrosion and metal release, and ii) determining the appropriate welding procedure and filler metal (316 L, 309 L, 312). All weld metals (WMs) showed a higher pitting corrosion susceptibility as compared to the base metal (BM). Under induced friction (stirring), WP significantly enhanced the metal release from all materials, which was accelerated between 1 and 3 days of exposure. Post-imaging indicated pits. 312-WM released significantly higher amounts of metals as compared to the BM and the other WMs. This study indicated that the presence of WP, friction, and weldment-induced corrosion susceptibilities could synergistically cause metal release and corrosion of food contact materials.
In this study, a facile, environmentally friendly, room-temperature synthesis of Ag-coated on microporous TiO 2-based catalysts and their application as a photocatalyst to degradation of penicillin as an antibiotic from pharmaceutical wastewater was investigated. The sol-gel method was used for the preparation of SiO 2 and SiO 2 @TiO 2. Then, the SiO 2 @TiO 2 was wrinkled using hydrothermal treatment. Finally, Ag as plasmonic material was doped on wrinkled photocat-alyst via wet chemistry approach. The synthesised photocatalysts were characterized using different analyses such as XRD, FTIR, RAMAN, FESEM, TEM, XPS. The results showed that the Ag was successfully coated on the wrinkled TiO 2 layer. The performance of the synthesised photocatalyst * Corresponding authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). was studied in terms of penicillin antibiotic removal from pharmaceutical wastewater in the range of visible light. The band gap energy (E g) of SiO 2 and after addition of TiO 2 and Ag was obtained 4.5 and 2.8-3.2 eV. Specific surface of SiO 2 and SiO 2 @WS-TiO 2 was found 293 and 329 m 2 /g respectively. The results indicated that wrinkling and coating Ag can enhance the SiO 2 @TiO 2 photocat-alyst activity for degradation of penicillin. Furthermore, the operating parameter of degradation of penicillin such pH, contact time, initial penicillin concentration, temperature, and the amount of synthesized photocatalyst was optimized. Finally, it was found that Langmuir isotherm model is well fitted with experimental data to predict kinetic of penicillin degradation. Ó 2022 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).
This paper presents numerical simulation of graphe nanoplatelet (GNP) – sodium dodecylbenzene sulfonate (SDBS) – water nanofluid with volumetric mass fractions of ϕ equal to 0–0.1%. The new microchannel is made of 2 layers and has sinusoidal cavities along with the heat sink. The study was conducted for Re = 50, 300, 700 and 1000 (laminar flow). Based on the results, higher Re leads to more convective heat transfer coefficient. Therefore, the value of temperature gradients decreases and on the other hand the effect of cooling fluid temperature in warm areas near solid wall becomes important. Using a higher value of Re results in the penetration of heat in the fluid layer decreases which in general will reduce the temperature of the outlet section in larger Re values. Also, larger Re value results in larger development length which is also a cause for lack of thermal development and dominance of the temperature of the coolant flow in the heat sink resulting in decreased outlet section temperature for higher Reynolds numbers. For Re = 50 and 300 because of lower fluid velocity, the effect of surface geometry factors such as sinusoidal paths or hollow parts (cavities) has a smaller influence on the pressure loss or friction factor of the flow.
Given the importance of the environment around the world and its accelerating destruction brought on by the increase in emissions resulting from the growing use of various forms of transportation, this paper shall aim to eliminate this research gap via a thorough investigation of the literature. These goals include the effect of greenhouse gases emitted by the transportation industry on the environment, the impact of pollutants on transportation mode choice, a study of the obstacles to reducing pollution in transportation, and the presentation of solutions and suggestions. In the research, papers related to this topic in various transportation industries, including road, rail, marine, air, and multimodal transportation, and the variables affecting the control of greenhouse gas emissions in any mode of transportation were collected. Afterward, fundamental analysis was carried out, conclusions drawn, and the presentation of suggestions and solutions in this area addressed. Reducing greenhouse gases in transportation is a challenge that requires examining numerous influential variables and factors. The studies presented in this research are expected to be useful, especially for the energy activists, researchers, and policymakers who would like to conduct long-term studies of pollutants in the transportation industry and the variables influencing the control of greenhouse gas emissions.
One of the most important and common criteria for evaluating the emergency medical systems is the response time, which is a function of the availability of an ambulance at the time of the request and the time that it takes for the ambulance to arrive at the call location. In this study, an optimization model is proposed to deal with the problem of the emergency medical service stations’ location and ambulance allocation. In order to capture the impacts of uncertainty in the network and obtain more realistic results, it is assumed that medical aid demands from any location in the city at any time slot of the day have a probabilistic distribution. In addition, to consider the traffic fluctuations in the modeling process, it is assumed that the arrival time to the request location is a time dependent variable. To deal with the complexity of the proposed approach and find optimal solutions in a reasonable execution time, some heuristic algorithms are suggested to solve the ambulance routing problem and the proposed non-linear integer model. To show the applicability of proposed models and algorithms in large-scale networks, the models and algorithms have been applied to the emergency medical system of the city of Isfahan, Iran. Three different scenarios are defined to improve the performance of the emergency medical services in Isfahan. The results show that relocating emergency medical service stations and reallocating ambulances will lead to significant improvements in both response time and coverage area in Isfahan.
In the current study, the physicochemical and emulsifying properties of modified waxy maize starch obtained through a new environmentally friendly method of esterification were evaluated. The starch modification was carried out in NaOH solution with different levels of octanoyl, myristoyl, and stearoyl chlorides. Increasing the fatty acid chlorides concentration led to the degree of substitution increment, while reaction efficiency and yield decreased. Based on fourier transform infrared spectroscopy results, the presence of two new bands of carbonyl (1740–1750 cm⁻¹) and carboxyl (1570 cm⁻¹) groups in the ester bond confirmed the successful starch esterification process. The level of 0.1 mL fatty acid chlorides/g of starch demonstrated the highest emulsifying properties. Upon esterification, the crystalline structure of amylopectin was destroyed, indicating no gelatinization features. Therefore, using the fatty acid chlorides in an alkaline condition could be suggested as a feasible way to modify waxy maize starch toward hydrophobicity increment with desirable properties.
The present work reports on a low-cost synthesis of new nanocomposites consisting of carbon dots (CDs) trapped in a matrix of titanium dioxide. The CDs were prepared directly from polyethylene glycol without any further purification and then trapped in a carbonized mesoporous crystalline TiO2 ([email protected]2). The as-prepared photocatalysts were characterized by XRD, FT‐IR, FESEM, XPS, PL, DRS, TGA, N2 adsorption-desorption, and Zeta potential techniques, after which their performance was investigated through degradation of both cationic and anionic organic contaminants. The optimized catalyst showed excellent photocatalytic activity for degradation of methylene blue, rhodamineB, and methyl orange, demonstrating higher efficiency than reference specimens, such as calcined-mTiO2, carbonized-mTiO2 or P25 under visible light irradiation. Its efficiency in decaying cationic dyes was found to be better under alkali conditions, while anionic dyes were better destroyed under acidic conditions. Thermogravimetric analysis and consecutive batch runs also displayed both thermal and chemical stability of the prepared [email protected]2 materials. The results of scavenging tests indicated that the main active sites in the photo-degradation of dyes were holes (h+) generated upon photoexcitation of titanium dioxide. The excellent performance of photocatalysts achieved in this study provides an important step toward the rational design of highly active photocatalysts.
In this paper, a mutant gray wolf optimization algorithm is proposed to solve the economic-environmental dispatch of integrated combined heat and power, heat only, and traditional thermal units considering the effects of temperature drop of the heat pipelines and valve-point effect. Also, constant mass flow and variable temperature strategy are used to control heat networks. Simulations are done on 24-units, 48-units and also 84-units test system and the results of mutant gray wolf optimization algorithm is compared with other methods. In order to make a fair judgment of the performance of the algorithms, each algorithm was run 30 times for each scenario and the best, worst, mean, and standard deviation of the results are calculated. The optimization results indicate the better performances of the proposed mutant gray wolf optimization algorithm than other meta-heuristic algorithms.
Salinity is a worldwide concern. The effects of CO2 enrichment and N sources under salinity on the vegetative, photosynthetic, and biochemical parameters of tomato was explored. The tomato plants are cultivated in two climate-controlled greenhouses with two CO2 levels: 300 (C1) and 700 (C2) ppm. Five NO3:NH4 ratios (25/75(N1), 50/50(N2), 75/25(N3), and 100/0 (N4)) were used to fertilize plants in two salinity conditions (0 (S1) and 50 mM (S2)). When NH4 was raised, vegetative, yield and biochemical characteristics were seen to decline. By increasing nitrate, yield, and desirable tomato characteristics such as fresh weight of shoot, root, and fruit, dry weight of shoot and fruit, and the number of fruits per plant, photosynthesis, and water content of shoot were enhanced. Increased CO2 mitigated the detrimental effects of salt stress. By increasing the nitrate in the ratio of NO3:NH4, notably in the S2N4 treatment, the rate of decrease of vegetative characteristics caused by salinity stress was greatly slowed. Under the detrimental influence of salinity stress, photosynthesis and transpiration improved in NO3:NH4, 50/50 (S2N2 treatment). In general, when the amount of ammonium was greater than nitrate (NO3:NH4 ratio of 25/75) in both saline and non-saline conditions, the examined attributes did not demonstrate a favorable influence on all features.
In this study, an electrospray synthesis approach was utilized in which a solution mixture of a sensitive bioactive agent, d-limonene (DL, R-(+)-Limonene), and a nature-inspired polymer, κ-carrageenan (κC) was applied to design DL-κC nanoparticles (NPs) in a one step process. The engineered DL-κC NPs displayed spherical morphology and the maximum encapsulation efficiency of NPs was about 97 % by altering the mass ratio of DL to κC. The developed DL-κC NPs showed a pH-dependent release manner in vitro. Both photostability and thermostability of DL were promoted by increasing the κC concentration, and >85 % of the original DL could be preserved following 120 min of UV-light exposure in the NPs with 0.5 % κC. The results demonstrated that electrosprayed κC NPs are promising candidates for the design of high-loading pH-sensitive NPs for encapsulation of highly sensitive bioactive agents.
Bioethanol was produced from wheat straw by a concentrated alkali pretreatment at specific conditions with a yield of 88 g ethanol per 1 kg of dry straw. To economically improve the bioethanol production process and valorize residual waste, the lignin-rich solid waste particles were isolated from the pretreatment waste liquid and characterized, and finally employed to reinforce starch-based biodegradable film. The solid waste particles were characterized by chemical analysis, dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). As bioethanol byproducts, they have mainly contained 88 wt% lignin. The average diameter of the uniform spherical shape extracted particles was determined to be 160 nm by DLS and FESEM. The presence of syringyl and guaiacyl rings were conducted by FTIR. Due to their suitable mechanical performance and thermal resistance, the lignin nanoparticles were employed as reinforcement for green biodegradable starch films. To prepare films, suspensions containing starch, glycerol, and different concentrations of lignin (0–30 wt%) were molded by the solution casting process. The starch-lignin composite films were analyzed by mechanical tensile tests, crystallinity analysis, FESEM, and thermal analysis. From the results, it was found that by adding 20 wt% lignin particles, the tensile strength and modulus of the pure starch film were increased from 4.8 and 0.9–8 and 2.4 MPa which can be partially explained due to crystallinity enhancement of film from 29 % to 48.3 %. In addition, the thermal resistance and the hydrophilic property of the composite films were enhanced due to lignin nanoparticle presence. It can be concluded that the isolation of lignin nanoparticles as waste solid in bioethanol production could be considered as a promising stage in the sustainability of second-generation products from the bioethanol production process.
The shortage of water resources and the increased demand for clean water warrant focused investigations on wastewater treatment. In this regard, mixed matrix membranes (MMMs) have been introduced as economic and efficient tools for removing contaminants from wastewater. The current study deals with the synthesis of a hydrazone-linked covalent organic framework (Hz-TFPTZ-COF) and its incorporation into polysulfone (PSf)/ poly N-vinylpyrrolidone (PVP) matrix to obtain [email protected]/PVP MMM containing different concentrations of Hz-TFPTZ-COF (0–1 wt%). The synthesized Hz-TFPTZ-COF and the prepared MMMs were fully characterized using various analytical techniques. The negative surface charge of Hz-TFPTZ-COF made it a good candidate for removing cationic dyes. Moreover, the effect of Hz-TFPTZ-COF loading on the mechanical properties, porosity, pure water permeability (PWP), and dye rejection of the prepared MMMs was investigated. Hz-TFPTZ-COF concentration as low as 1.0 wt% in the MMM formulation yielded a PWP as high as 94.69 L. m⁻². h⁻¹. bar⁻¹ and dye rejection of 92% and 88% for Basic Blue 41 and Methyl Violet, respectively. In addition, the tensile strength of the prepared MMMs was increased from 2.26 to 3.43 MPa. Overall, incorporating the Hz-TFPTZ-COF into PSf/PVP polymeric matrix affords a MMM with superior performance in the purification of cationic dye wastewater.
Let G be a graph with the vertex set {v1,…,vn}. The Seidel matrix of G is an n×n matrix whose diagonal entries are zero, ij-th entry is −1 if vi and vj are adjacent and otherwise is 1. The Seidel energy of G, denoted by E(S(G)), is defined to be the sum of absolute values of all eigenvalues of the Seidel matrix of G. In Akbari et al. (2020), the authors proved that the Seidel energy of any graph of order n is at least 2n−2. In this study, we improve the aforementioned lower bound for tree graphs.
In the last decades, due to the increasing environmental concerns such as energy-resource depletion and global warming, energy efficiency instruments and renewable energy production has been promoted more than ever. This paper investigates a comprehensive comparison between two energy markets, i.e., the tradable white certificate (TWC) market and the tradable green certificate (TGC) market. How to coordinate the two energy markets and what the coordination impacts become the main issues under a reward-penalty mechanism. This multi-agent problem is discussed in an electricity supply chain consisting of two populations of traditional energy suppliers who want to decide about using one of them under government intervention. In this regard, the behavior of the suppliers is analyzed under three different Scenarios, including traditional power generation, energy efficiency program (EEP), and renewable portfolio standards (RPSs). An evolutionary game is applied to formulate the problem. The results show that a mandatory fine policy is more useful than an energy-saving subsidy to motivate the traditional suppliers to move toward sustainable energy generation. This policy also helps governments to meet their sustainable-oriented goals, as we discussed in this work. The findings can be applied to extend sustainable-based energy projects in developing countries.
In the Irano–Himalayan karst bauxite belt, in northwestern Iran, karst bauxite orebodies are widespread. Although several of these orebodies have been characterized, no comprehensive data are available for the early Jurassic karst bauxite ores. The early Jurassic Soleiman Kandi karst bauxite deposit consists of a mineral assemblage of diaspore, hematite, kaolinite, and rutile, with lesser amounts of illite, pyrophyllite, chlorite, siderite, amesite, and quartz. The ores are characterized by similar Eu/Eu*, Sm/Nd, and Nb/Ta ratios, suggesting that they share the provenance from a mafic protolith. R-mode factor analysis indicates that most of the variance of the dataset is explained by a factor accounting for an inverse relationship between the clay minerals–diaspore–rutile–resistant minerals (e.g., zircon and monazite) pool and hematite, driven by redox fluctuations related to an upward decrease in Eh under dry climate. The other two factors are related to the capability of clay minerals in controlling the distribution of bivalent large ion lithophile elements Ba and Sr, and also to the control exerted by authigenic fluorocarbonates on rare earth elements (REE: La-Lu) + Y distribution. The Soleiman Kandi karst bauxite ores are enriched in critical raw materials, including V, Co, Ga, and Ta, with respect to the average Upper Continental Crust. Among these elements, Ta is particularly abundant, probably as a consequence of the occurrence of a Ta-rich variety of rutile, representing a peculiar feature of the Soleiman Kandi bauxite deposit.
To guarantee continuous and reliable operation of power systems working near their stability margins, it is necessary to clear faults quickly. For this purpose, accurate and fast fault location methods are required. Single-ended phasor based methods are a category of fault location strategies which are favourable due to simplicity of their implementation. However, enhancing the accuracy of these methods is a challenging task due to unavailability of data from the remote end of the line. In this paper, a novel fault location method that requires the measured data of one end of the line is proposed. As a result, this method does not need communication links. The proposed method is bi-level and in its first level, fault characteristics such as current, voltage, and impedance of the fault are calculated for a given fault location obtained from Level-2. Then, based on the calculated fault characteristics, fault location is updated in the second level. The presented fault location method considers magnetic coupling between lines and it is also applicable for both transposed and un-transposed lines. Numerous simulation studies verify the accuracy of the proposed method in presence of uncertainties such as noise, fault impedance and error in input line parameters. Furthermore, although the proposed method is based on a bi-level iterative approach, the presented results confirm that it converges quickly in 2 or 3 iterations.
Metal-organic frameworks (MOFs) have escalated much attention as innovative electrode materials for supercapacitors applications due to their high porosity, adequate active sites, and tunable structures. However, most MOFs show low capacitance, which limits their application in energy storage devices. In this study, a new MOF composite containing poly(4-aminothiophenol) (PAT), Zn, Ni, and reduced graphene oxide (rGO), abbreviated as PATZ1N2G2-MOF, was fabricated by a one-step simple hydrothermal method and its electrochemical characteristics for supercapacitor applications were examined. The structural characterization of the proposed MOF exhibited successful synthesis of a highly porous and nanoscale crystalline spherical PATZ1N2G2-MOF configuration mainly spread on extra thin nano-sheets of rGO. The convenient mixed spherical structure of PATZ1N2-MOF and rGO Nano-sheets facilitates more electrochemically active regions and more accessible routes for charge and mass transfer, developing a specific capacitance as high as 1230.23F g⁻¹ at a current density of 1.0 A g⁻¹ as well as excellent capacitance retention of 89.8% after 3000 repetitive cycles. Moreover, the capacity of the modified positive electrode for the 2-electrode setup was obtained to be 93.31F g⁻¹, producing a high energy and power density of 33.17 Wh kg⁻¹ and 188.35 W kg⁻¹, respectively. The experimental results revealed the superior supercapacitive behavior of the PATZ1N2G2-MOF/NF electrode.
Green chelating ligands are being increasingly produced and commercialized globally because conventional ligands such as ethylenediamine tetraacetate (EDTA) are poorly biodegradable and persistent in the environment. The study of toxic metal remobilization processes from minerals by new chelating ligands is crucial to better understand the fate and transport of metals in soil and sediment environments. In this research, the effects of two green alternatives of EDTA, i.e., glutamate diacetate (GLDA) and methylglycine diacetate (MGDA), on lead (Pb) remobilization kinetics from Pb-loaded montmorillonite (MMT) were studied at two ligand concentrations of 0.25 and 1.0 mM. The effects of a 30-day residence time on the rate and quantity of Pb remobilization were also evaluated. The results showed that the time-dependent Pb remobilization was biphasic with an initial rapid phase lasting 3 h followed by a slow phase taking 12 h. The degree of Pb remobilization was governed by the nature and concentration of the chelating ligands presented in the systems. The capacity of the ligands to remobilize Pb from MMT was in the order EDTA > > MGDA > GLDA, according to the decreasing order in the stability constants of their complexes with Pb ions. The aging of the MMT systems caused a significant reduction in both Pb remobilization quantity and rate parameters. The results suggest that GLDA and MGDA have a significantly lower Pb-remobilizing impact than EDTA in contaminated soil and sediments containing MMT as a major clay constituent.
Nutrients and nitrate move to the boundary of the wetted zone under drip-tape irrigation (DTI) of row crops, so irrigation depth, wetted width, and irrigation frequency are the most important factors in managing the wetting front and keeping N in the root zone. Many farmers in arid regions who have changed their irrigation systems to DTI, but they are still applying N in two splits as they are used for surface and sprinkler irrigation. Crop models can be used to optimize the timing and amount of nitrogen fertilizer applied to minimize both N leaching and the amount of N remaining in the soil after harvest. The objectives of this study were to calibrate the Cropping System Model (CSM)-CERES-Maize for two maize hybrids and to evaluate the model under DTI with two different soil wetting widths. The single cross Hybrid 704 (SC704) grown in two experimental fields (Exp-1 and Exp-2) and the single cross Hybrid 606 (SC606) grown in one experimental field and two farmer fields (Exp-3, Ff-1 and Ff-2) were evaluated during three years (2016, 2017 and 2019). Plant traits including leaf area index (LAI), total biomass (TB), soil moisture (SM), nitrogen uptake (NU) and water productivity (WP) were measured. Soil NO3-N was measured at three distances from the planting row and three soil depths in Exp-1 and Exp-3 during two maize growth stages. The fraction of the wetted width (fw) along drip-tape was 70% in Exp-1% and 100% in Exp-3 (referred to as fw-70 and fw-100, respectively). The results showed good performance of the model for simulating TB and LAI with NRMSE < 21.9% for the two hybrids in the applied N fertilizer treatments. The accuracy of the simulation of SM and WP in fw-100 was better than that of fw-70. Simulated NO3-N followed the observed trend for fw-100, while model performance varied for the different irrigation and N levels in fw-70. Model accuracy for soil NO3-N prediction decreased for the high N fertilizer application under deficit irrigation management. These differences were related to the wetting pattern volume, the distribution of N in the soil profile, and accumulation of soil N under DTI. Overall, the model can simulate TB and NU with high accuracy, SM with good accuracy, and soil NO3-N with an acceptable accuracy under DTI. The accuracy of the model was also higher for the unlimited wetting width, as compared to the limited one. This study showed that the CSM-CERES-Maize model can be used for evaluation of nitrogen management practices for drip irrigated maize grown under arid conditions.
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6,678 members
Mansour Nejati
  • Department of Electrical and Computer Engineering
Mehdi Amirnasr
  • Department of Chemistry
Salar Dorafshan
  • Department of Natural Resources, Division of Fisheries
Saeid Eslamian
  • Department of Irrigation
Mohammadhossein Fathi
  • Department of Materials Engineering
Information
Address
Isfahan University of Technology, 84156-83111, Isfahan, Isfahan, Iran
Head of institution
Dr. Mahdi Abtahi
Website
www.iut.ac.ir
Phone
+98 31-33912210
Fax
+98 31-33912862